The federal investigation into the firing of nine U.S. attorneys could jolt the political landscape ahead of the November elections, according to several people close to the inquiry.

Washington’s attention has been diverted from the scandal since the August resignation of Alberto Gonzales as attorney general, and has focused instead on Democrats’ efforts to hold White House officials in contempt for ignoring congressional subpoenas to testify on Capitol Hill about the firings.

But recent behind-the-scenes activity in several investigations suggests that the issue that roiled Congress in 2007 could re-emerge in the heat of the election year. Two inquiries by the House and Senate ethics committees are examining whether several congressional Republicans, including one running for the Senate this year, improperly interfered with investigations.

As potent as the congressional probes might be, they appear to be far narrower than a sprawling inquiry launched by the Justice Department’s Office of Inspector General (OIG) and the Office of Professional Responsibility (OPR).

Investigators from these offices have been questioning whether senior officials lied to Congress, violated the criminal provisions in the Hatch Act, tampered with witnesses preparing to testify to Congress, obstructed justice, took improper political considerations into account during the hiring and firing of U.S. attorneys and created widespread problems in the department’s Civil Rights Division, according to several people familiar with the investigation.

The internal Justice Department probe cannot bring charges but can refer findings to a U.S. attorney for the District of Columbia or a special prosecutor, who could then pursue a criminal investigation. One source close to the investigation expects the offices to issue a scathing report within the next three months, but they have not announced a timeline for their joint inquiry.

“I think it could be historic,” said David Iglesias, former U.S. attorney in New Mexico, who was one of the nine ordered to resign by the Bush administration. “Arguably it’s the most significant investigation OPR and OIG have done in a generation, or maybe ever.